Ruined credit score due to Cell C ***** up

I am trying to clear my credit record from a payment that kept on bouncing because I left enough money in my account for the value of my cellphone bill to go off. Unknown to me I had a 2nd contract that the store clerk NEVER CANCELLED. So now my credit record is trashed. Trying to rectify it is impossible because the phone just rings. I've been on the line 3 x 40min.

PLEASE CALL ME and help me rectify this.... plz